Record changer for phonographs



Dec. 11, 1945. H. v. ALEXANDERSVSON ET AL 2,390,862

RECORD CHANGER F OR PHONOGRAPHS Filed Jan. 8, 1943 Patented Dec. 11,' 1945 RECORD CHANGER FOR PHONOGRAPHS Harald Valdemar Alexandersson and Nils Uno Hagren, Lidingo, Sweden, assignors to Svenska Aktiebolaget Gasaccumulator, Lidingo, near Stockholm, Sweden, a corporation of Sweden Application January 8, 1943, Serial No. 471,712 In Sweden March 20, 1942 3 Claims.

Our invention relates to an arrangement in recrd changers for phonographs with disc controlled record changing.

Certain kinds of record changer arrangements for phonograph'sare controlled by means of a disc which does not rotate during the playing of a record, but immediately after the record has been fully played is caused to revolve in order to initiate the operations connected with the record changing. One.method for starting the rotation of the disc has been to drive it by means of a. friction wheel or a cog-wheel, cooperating with its periphery or possibly with the periphery of another wheel, placed in motion transferring relation to the disc. In order that this shall not continuously drive the disc, the latter is provided with a recess in its periphery, in which the friction roller turns freely during the playing. In.

order that the movement of the disc shall be started, means are provided to give it an impulse in the correct direction, so that the friction roller engages the periphery adjacent to the recess.

In known arrangements of this kind compli-. cated means has been required to give this impulse. The impulse should take place as a result of th needle entering the final groove in the record, which is for this purpose as a rule provided with an increased pitch. A plurality of different arrangements have been proposed in order to start the record changing by means of the increased speed with which the needle will move inwards during the passage through the final or tripping groove, but all these arrangements will, when combined with a record changer arrangement of the above mentioned kind, in which the record changing is controlled by means of a disc,

* be rather complicated.

The present invention refers to an arrangement for providing the starting impulse for record changing arrangements of the above mentioned kind, which is substantially simpler than the arrangements hitherto used for the same purpose, and which may due to its simplicity be manufactured in a more durable and strong manner, and which is consequently more reliable in operation and simultaneously cheaper in production.

The invention will be described below in connection with the annexed drawing, in which Fig. 1 shows a part of the starting arrangement in horizontal projection, and Fig. 2 shows the corresponding part in vertical projection. In Fig. 1

reference character l0 indicates the shaft of the tumtable. It is assumed that the arrangement is seen from above with the turntable removed, but

roller l2 of thedisc as well as the disc l3 therefore being visible in Fig. l. The above mentioned recess in the periphery of the disc is indicated I4, and as the arrangement in the position, indicated in Fig. 1, is assumed to be in its normal playing position, the disc is stationary, the driving roller l2 rotating freely in the recess H.

The turntable shaft carrying the pickup arm is indicated Hi. It will be evident from Fig. 2

how thi cooperates with the above mentioned means as well as with the pickup arm Hi. The pickup arm is carried in the usual manner by a bearing arrangement ll, through which the shaft extends, and which contains the required means for providing the raising and lowering of the pickup arm in connection with the record changing. As this means, however, has no function in connection with the present invention, it has not been shown in Fig. '2. A thin blade spring i8 is frictionally engaged between two collars l9 and 20 on the shaft l5. This blade spring preferably extends between the turntable II and the disc I3 to the vicinity of the shaft l0 and the driving roller l2 of the cam disc [3, where-a projection 2| extends upwardly from the spring l8.

On the shaft l0 below the turntable there is mounted a bushing 22, provided with a pin 23 directed downwardsi Furthere, the disc I3 is provided with a cam surface 24 elevated above the level of the disc, which isformed with a vertical face 25 and with an inclined face 26 which rises from the-surface of the disc.

The arrangement operates in the following manner: During the playing of a record the pickup arm is continuously turned towards the centre of the record du to the cooperation with the spiral groove 'inthe record and the needle, thus turning the shaft l5 and the collars l9 and 20.

mounted thereon. The spring l8, which isfrictionally engaged between these collars, therefore will also turn a corresponding distancefor each revolution of the record and thus the spring I8 i moved closer to the shaft Ill; The pin 23 hence strikes the projection 2I' on the spring,

which is thereby displaced back to a position just clearing the pin 23. During the following revolution of the turntable the spring will again be turned inwards a distance, corresponding t one groove-width, and the pin 23 will again strike the projection 2|, the spring will again be, turned back. Duringthis movement to and 'fro the indicated byth'e broken line H, and the driving spring will ride on the outmost part of the cam surface 24.

When the record is fully' played, the pitch of the tripping groove increases substantially, and hence the spring I8 is turned a greater distance than any time former during the passage of the needle in the turns of the sound groove. This movement is sufficiently great that the spring rides over the top of the cam 24 and engages the vertical face 25. During the following revolution of the pin 23 the latter strikes the spring I8 and turns it back, but due to the engagementof the spring with the vertical face 25, the disc I3 is turned sumciently to cause the roller I2 to ride up on the periphery of the disc I3, whereby this disc is turned one revolution until the roller I2 again enters the recess I4. During this movement the disc, in a manner which forms no part of the present invention, causes the operations involved in the record changing to be carried out, namely the elevation of the pickup arm from the record just played, the swinging out of the pickup arm into a position beyond the record, the placing of a new record on the turntable, the turning inwards of the pickup arm into a position immediately over the initial groove of the new record and the lowering of the pickup arm into this groove.

During the movement of the pickup arm the spring I8 follows the arm in its movement, as

far as is permitted in one direction by a stop pin 21 and in the other direction by the pin 23. ,It should be observed that during this part of the cycle, the spring-l8 does not cooperate with the vertical face 25 on the cam 24 as the rotation' of the disc I3 by the r ler I2 moves the cam 24 away from the spring. When the record changing is almost completed, suitably'during the period when the pickup arm is lowered into the initial groove of the new record the inclined face 28 of the cam strikes the spring I8, whereby the spring is again elevated into its normal working position, and the playing of the new record begins.

During the starting impulse the disc will be driven by means of two independently acting forces, namely that resulting fromthe cooperation between thespring I8 and the vertical face 25 and that resulting from the engagement by the roller I2 with the periphery of the disc. this roller, which is usually rubber covered, becomes worn, its diameter will decrease, and hence it is evident that an initial adjustment of the two driving means so that both tend to turn the disc at the same speed cannot be maintained. A reduction in the diameter of the roller results in.the latter tending to drive the disc at a slower speed than the cam 24 and spring I8 tend to drive respect to the roller, thus further wearing the rubber surface of the latter. In order to obviate this, the spring I8 is made as a thin blade spring, and the projection is spaced somewhat above the level of this spring. As long as there is no other resistance to the movement of the spring by the pin 23 than the friction between the collars I9 and 20, no substantial deformation of thespring I8 will take place. If, however, the friction roller I2 should intend to drive the cam disc I3 at a lower speed than that at which the spring I8 drives it, the turning moment resulting from the Qforce applied by the pin 23 to the projection 2| will cause a torsion turning of the spring I8,

which compensates for the difference in speed.

The invention is, of course,v not. limited to the form shown in detail and described, but substantial modifications may be madewithin its scope Thus, for instance, the turning'movement of the spring I8 may be provided by another means than the shaft I5, if said means is in movement transferring relation with said shaft. The pin 23 may also be arranged in connection with another shaft than the driving shaft of the turntable.

What we claim is: 1. In a phonograph, a turntable, means for rotating said turntable, a vertical shaft, a pickup arm mounted on said shaft so as to be turnable in a horizontal plane with said shaft for cooperating with a record on said turntable, a rotatably mounted record-change initiating disc, a cam on said disc having an abrupt face, a pair of collars fixed to said shaft, a cam: actuating arm frictionally engaged between said collars so .as to be turned a predetermined distance towards engagement with said cam face by turning of said pickup arm and shaft during each revolution of said turntable when said Pickup arm is cooperating with the playing groove of said record, and

'a member movable in a circular path in timed relation to said turntable, said path intersecting the path of movement of said actuating arm as the latter approaches said cam face whereby the "actuating arm 'is moved back once during each revolution of said member, said predetermined distance of movement of said actuating arm being insuificient to bring it into engagement with said cam face before it is moved back by said member, said actuating arm being moved a greater distance when said pickup arm cooperates with the tripping groove of said record so as it. This would result in the disc slipping with I to engage said cam face before the actuating arm is moved back by said member, whereby subsequent movement of said actuating arm by said member actuates said cam.

2. In a phonograph, a turntable, means for rotating said turntable, a vertical shaft, a pickup arm mounted on said shaft so as to be turnable in a horizontal plane with said shaft for cooperating with a record on said turntable, a. rotatably mounted record-change initiating disc, a cam on said disc having an abrupt face, a friction roller normally freely rotatable in a recess formed in' the'periphery of said disc, a cam "actuating arm frictionally engaged-by 'said shaft so as to be turned a predetermined distance towards engagement with said cam face by turning of said pickup arm and shaft during each revolution of said turntable when said pickup arm is cooperating with the playing groove of said record, and a member movable in a circular path in timed relation to said turntable, said path intersecting the path of movement of said actuating arm as the latter approaches said cam face whereby the actuating arm is moved back once during each revolution of said member, said predetermined distance of movement of said actuating arm being insufficient to bring it into engagement with said cam face before it is moved back by said memher, said actuating arm being moved a greater distance when said pickup arm cooperates with the tripping groove'of said record so as to engage said cam face before the actuating arm is moved back by said member, whereby subsequent movement of said actuating arm by said memberactuates said cam to rotate said disc into frictional engagement with said roller, said actuating arm being resiliently yieldable between its points of contactwith said member and said cam face tocompensate for any inequality between the rate at which the disc is driven by the roller and the rate at which said member tends to drive the disc.

3. In a phonograph, aturntable, means for r0- tating said turntable, a vertical shaft, a pickup arm mounted on said shaft so as to be turnable in a horizontal plane with said shaft for cooperating with a record on said turntable, a rotatably mounted record-change initiating disc, a cam on said disc having an abrupt face, a friction roller normally freely rotatable in a recess formed in the peripher of said disc, a resiliently yieldable cam actuating arm frictionally engaged by said shaft so as to be turned a predetermined distance towards engagement with said cam face by turning of said pickup arm and shaft during each revolution of said turntable when said pickup arm is cooperating with the playing groove of said record, a lateral projection offset with respect to the center line of said actuating arm, and a member movable in a circular path in timed relation to said turntable, said path intersecting the path of movement of said projection as the actuating arm approaches said cam face whereby the actuating arm is moved'once during each revolution of said member, said predetermined distance of movement of said actuating arm being insuflicient to bring it into engagement with said cam face'before it is moved back by said member, said actuating arm being moved a greater distance when said pickup arm cooperates with the HARAID VALDEMAR ALEXANDERSSON. NILS UNO HAGREN. 

